First thing first, Dragon Gobies are Brackish water fish, some people have had success in
FW but it's maybe 1 out of 1,000. No, I don't consider one year a success

.
I keep mine in Brackish Water at a
SG of 1.010 and it shares a 55 gallon tank with a clay goby, see my gallery for pics.
95% of the time it gets Wardley Shrimp Pellets as these break up in the water allowing it to eat more and quicker. The other 5% of the time it gets either an algae waefer or frozen raw shrimp that has been cut up into very fine pieces. They also eat blood worms but I'm allergic to those so it's not an option for me.
I've had this one for about 2 years now. They are slow growers, keep feeding it and keep the water clean and it will grow bigger for you.
BTW.. the largest VG in captivity was recorded at 27" long and 5-6 years old. This will give you an idea of how large they can grow.
Any other questions feel free to ask.